Carbon
:''C redirects here. For an article on the speed of light, see speed of light.'' Carbon is a chemical element with the symbol C and atomic number 6 on the periodic table. It is a non-metal and the basis for the great variety of chemical compounds that make up organic life. Carbon is tetravalent and thus able to form covalent chemical bonds with a wide variety of other chemical elements, such as hydrogen, oxygen, chlorine, and nitrogen – to name a few – and most notably with other carbon atoms. Carbon atoms can bond to each other to form open-chain compounds or cyclic (ring) compounds - both of which may have branches - ultimately resulting in a vast number and variety of complex compounds and molecules often vital to organic functionality and life support. Without carbon, the basis for life as we know it would be impossible. Before determinations of the age of carbonaceous materials could be made on a quantum level, radiocarbon dating was used to determine the age of organic materials. Carbon is very widely-distributed throughout stars, comets, and atmospheres of many planets. On Earth it is found in the atmosphere as CO2, in carbonates like limestone, and in coal, petroleum, and natural gas - the fossil fuels. Carbon is the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. Carbon has at least three forms, called allotropes, the best known of which are graphite and diamond. Another form, known as "white" carbon, now exists. Graphite is one of the softest known materials, mainly due the flat sheets of carbon atoms that only cling together weakly, while diamond is one of the hardest - consisting of C atoms connecting to four others at the corners of a tetrahedron, resulting in an extremely hard, dense compound. Energy from stars and thus the fusion mechanism powering stars can be attributed partially to the carbon-nitrogen cycle. Carbon-70 was used in the casing of combadges along with beryllium, silicon and gold. The term refers not to an isotope (as a carbon atom containing six protons and 64 neutrons would be extremely unstable), but an allotrope comprised of seventy ordinary carbon atoms in a geodesic configuration commonly called a "fullerene". Carbon was used in the making of carbon steel. ( ) In 2153, Arctic Archaeology Team scientist found some carbon traces in the debris field in the Arctic Circle. ( ) In 2154, Commander "Trip" Tucker and Ensign Hoshi Sato from were infected with a silicon-based virus on an M class planet. Doctor Phlox was unable to devise a treatment for them, because the virus was incompatible with carbon-based lifeforms. ( ) The Federation's offer to purchase the rights to the Barzan wormhole included that the Barzans were to provide the carbon compound structural elements for construction of an orbital facility. ( ) Kira Nerys told the Bajoran farmer Mullibok after supper in his cottage that he couldn't stay on Jerrado. Once the tapping started, the crust would release sulfur and carbon compounds that would make the air unbreathable. ( ) See also * Carbon dating * Carbon reaction chamber External link * de:Kohlenstoff ja:炭素 nl:Koolstof Category:Elements